Alloy steel for metal-cutting tools



iTNT FE.

EDWIN oonnme or xnnwoon,

Ann rnnc A. E. ARMSTRONG, or LOUDONVILLE,

NEW YORK.

ALLOY S'JJEIEJD FOR METAL-CUTTING TOOLS.

No Drawing. Application filed October 29, 1920, Serial NO. 420;432. Renewed OctOberB, 1923.

To all whom it may concern Be it known that we, EDWIN CORNING, a citizen of the United States, and a resident of Kenwood, county of Albany, and State of New York, and PERCY A. E. ARMSTRONG, a subject of the King of Great Britain, and a resident of Loudonville, county of Albany, and State of New York, have invented a new and useful Alloy Steel for Metal-Cutting Tools, of which the following is a specification.

Our invention relates to alloy steel for metal cutting tools, having properties gen erally intermediate between carbon steel and high speed, steel.

For small metal cutting tools, such as drills, taps, reamers and the like, carbon steel answers sufliciently Well, takes a keen cutting edge and produces smooth finished work, but is limited in its application, be cause under heat it softens and dulls rapidly.

High speed steel, which is commonly used for somewhat larger drills and similar tools which have to withstand greater heat, is not,

' of course, rapidly softened b frictional heat,

but, in addition to its big price, has the objection that the work produced is not so smooth and well finished as can be obtained by sharp edge carbon steel tools, for example, and a subsequent separate finishing operation is usually required. For example, drilled holes require finish reaming to produce satisfactory work. Furthermore, in the case of taps, for example, the teeth of the tap are often injured by the high temperatures re quired for heat treatment of high speed steel.

According to the present invention, an alloysteel is produced which is inexpensive to make as it contains about 95% or more of iron, the alloying constituents forming only a comparatively small part of the steel. The steel of the resent invention contains chromium, vanadium and molybdenum and also contains silicon considerably in excess of the usual silicon content Of steel, silicon being present in our improved alloy steel prefer ably to the extent of about 1%. This steel is hard and strong, takes'and holds'a keen cutting edge which is not materially softened, so as to become dulled, up to a temperature of about 650 F., and when made into tools for cutting metal, such as drills, taps, reamers and the like, can be used for the production of smooth finished work, without the necessity for separate finishing operations,-

and does not require heat treatment at such high temperatures as in the case of high speed steel, so that there is practically no tendency for any burnin off of the tips of the teeth of taps and similar tools during heat treatment. This steel has other features of advantage as hereinafter stated.

A good typical composition for an alloy steel in accordance with the present invention is as follows:

- Per cent.

Carbon 1.10 Silicon 1 Chromium 1. Molybdenum 1 'Vanadium .25

Manganese .25

and the remainder iron. Tools made from material of this composition give surprisingly good results in use, it being found possible, for example, with twist drills made therefrom to drill many times the number of holes possible with ordinary twist drills, before the drill has to be resharpened.

Drills were made from steel substantially Per cent. Carbon 1.05 to 1.20 Silicon .85 to 1.10 Molybdenum .85 to 1.10' Chromium .85 to 1.10 Vanadium .15 to .30 Manganese .20 to .50

The manganese can be dispensed with, if de sired, and relatively small proportions of other. materials commonly encountered in steel may, of course, be present.

Our improved alloy steel has a wide range of hardening temperatures. When heated to about 1500 F. and quenched in oil or water it has great hardness.

When heated 1m The steel works well in the mill,

to about 1850 F. and'quenched the be st results appear to be secured and aiveryeircel:

lent metal cutting steel is produced, with excellent strength and wear resisting prop- Such heating should very short time at-such-heat, preferably-not to exceed about one-half minute, is sufiicient.

- This steel is-,'o'ne of the hardest steels which has been produced and when properly.

heat treated has a Brinell hardness of. about 725-7 50. When drawn to 600? the Brinell hardness isstill about,fZO0.

does not seam and can be cast into very smooth ingots. Tn rolling the temperature should not be carried unduly high and-should preferably be kept under 2100 F. The steel will anneal and become quite easy; to machine when properly annealed. There is very little tendency for thisalloy. combination to move, that is .to say,-to exhibit tendency to warping, pr other malformationupon heating up and quenching, which is a feature of great advantage in heat treatment of tools. The characterlstic. grinding. spark given ed in grinding articles made of our improved alloy steel, which does not contain tungsten,

is markedly difi'erent from the tungsten colored spark. This is a feature of marked adea ers vantage both in manufacture and use, as this alloy steel .canbe readily distinguished from high speed steels by observation of the spark produced upon grinding. The foregoing applies whether the alloy steel is in the annealed or hardened state.

. We claim:

1. As a new composition of matter, an -alloyjsteel of analysis substantially as fol-.

lows: carbon 1.10%, silicon 1%, chromium 1%, molybdenum 1%, vanadium manganese 25%, and the principal part of the remainder iron. 2. As a new composition or matter, an al- 10y steel of analysis substantially as follows: carbon 1.05 to 1.20%, silicon .85 to 1.10%,

molybdenum .85 ,to 1.10%, chromium .85 to 1.10%, vanadium .15 to manganese below .50%, and the principal part or the remainder iron 3. Metal cutting tools made from alloy steel as claimed'in claim 1.

. 4. Metal cuttingtools made from alloy steel as claimed inclaim 2.

5. Drills for drilling metal made from alloy steel as claimed in claim 1.

6. Drills for drilling metal made from alloy steel as claimed'in claim 2..

In witness whereof, .we have signed our names hereto.

EDVVTN 'CURNTNG. PERCY A. E. ARMSTRQNG. 

